The present invention relates generally to radiation therapy and strategies for programming a radiation therapy machine, in particular a photon radiation therapy machine also referred to as a linear accelerator. More particularly the invention relates to a system for determining a radiation treatment plan, a corresponding method and a radiation therapy machine. The invention also relates to a computer program product, a computer readable medium and a radiation therapy method.
Radiation therapy may be employed to treat tumorous tissue. In radiation therapy, a high-energy beam of radiation is aimed towards a patient. More precisely, a radiation source produces a beam of radiation that is collimated and directed into a target volume in the patient. The level and placement of the dose must be accurately controlled to, on the one hand, ensure that the tumor receives sufficient radiation; and, on the other hand, that damage to the surrounding healthy tissue is minimized. Before performing the radiation therapy, a radiation treatment plan is determined in a radiation planning session. This allows an accurate and precise dosage of radiation to be delivered to the patient.
However, it is far from trivial to establish an optimal radiation treatment plan. The radiation fields may need to be highly complex, in the sense that the apertures formed by the beam collimator are small and irregular, in order to render the radiation dose to conform closely to a tumor volume. Complex treatment plans generally have long treatment delivery times. This is undesirable under circumstances where clinical resources are limited, and because a prolonged delivery time means a greater patient exposure to harmful leakage and scatter radiation. Furthermore, a treatment plan of low complexity is advantageous compared with a more complex treatment plan because it is less sensitive to geometric errors, such as patient misalignment and organ motion, and easier to quality assure.
U.S. Pat. No. 7,266,175 describes a solution for controlling the correlation between the factors of treatment plan efficiency and dosimetric fitness to optimize the radiation therapy, or radiotherapy plan, including providing user control of the segment count, number of monitor units (MUs), and selection of an optimization algorithm.